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Biomedical subjects

M Torabinejad

Publications and source records attributed to M Torabinejad.

At least 73 records · Page 4Linked to original sources
PubMed1993

Antibacterial effects of various endodontic medicaments on selected anaerobic bacteria.

This study was undertaken to determine the antibacterial effects of various endodontic medicaments against six selected anaerobic bacteria. The experiment involved the testing of the vapors of six medicaments using agar plates streaked with the bacteria. A zone of inhibition was recorded for each plate and the results were analyzed statistically. Formocresol produced significantly larger zones of inhibition than any of the other medicaments.

Analysis of Variance↗
PubMed1993

Presence of natural killer cells in human chronic periapical lesions.

Natural killer (NK) cells are lymphoid in nature and appear to kill target cells (neoplastic and virus-infected cells) without apparent prior immunization. Ten human chronic periapical lesions were examined for the presence of these cells. The lesions were collected, frozen in liquid nitrogen, and sectioned. They were then stained with an indirect immunoperoxidase procedure for the presence of human NK cells. Human tonsils and human periapical scar tissue were used as positive and negative controls. The results showed absence of NK cells in scar tissue and the presence of NK cells in tonsils and all samples of human periapical lesions. NK cells may play a defensive role in controlling root canal infections or, possibly, a role in its pathogenesis.

Adult↗
PubMed1993

Antibacterial effects of various endodontic irrigants on selected anaerobic bacteria.

This study was undertaken to determine the antibacterial effects of various endodontic irrigants against six selected anaerobic bacteria. The organisms were mixed separately with dilutions of each of the irrigants in tubes containing fluid thioglycollate broth and allowed to remain in contact for specific time periods before being evaluated for growth. Of the six irrigants tested, chlorhexidine appeared to be the most effective antibacterial substance. Hydrogen peroxide, sodium hypochlorite and REDTA were less effective while the calcium hydroxide and saline solutions proved to be totally ineffective.

Bacteria, Anaerobic↗
PubMed1993

Clinical diagnosis and treatment of endodontic and periodontal lesions.

Because of the intimate relationship of the root canal system and the periodontium, developing endodontic and periodontal lesions may mimic each other in clinical and radiographic appearance. The etiology, diagnosis, treatment, and prognosis of endodontic and periodontal lesions will be discussed.

Dental Pulp Diseases↗
PubMed1992

A computed tomographic study of the distances between the maxillary sinus floor and the apices of the maxillary posterior teeth.

The mean distance between the apices of the maxillary posterior teeth and the floor of the maxillary sinus was measured from computed tomographic display data from 12 autopsy specimens and 38 human subjects. The distance from these apices to the adjacent lateral bony surfaces was also measured. The apex of the mesiobuccal root of the maxillary second molar was closest to the sinus floor (mean 1.97 mm) but farthest from the buccal bony surface (mean 4.45 mm). The apex of the buccal root of the maxillary first premolar was closest to the adjacent lateral bony surface (mean 1.63 mm) but farthest from the floor of the sinus (mean 7.05 mm).

Bicuspid↗
PubMed1992

Coronal dye penetration of the apical filling materials after post space preparation.

Forty canals of palatal and distal roots of molars were cleaned and shaped with the use of a step-back technique. Thirty canals were obturated, 10 each with lateral, vertical, and thermafil techniques. Five root canals were obturated without a root canal sealer and served as positive controls. Another five root canals were obturated, and their coronal half was sealed with sticky wax and served as negative controls. The apical 5 to 6 mm of the filling materials were exposed to india ink for 48 hours. The depth of dye penetration was measured in all groups and statistically analyzed. The apical plugs in the thermafil group had the highest degree of coronal leakage. The ANOVA test showed a significant statistical difference between coronal dye leakage between this group and those found in canals filled by lateral or vertical condensation techniques. The results indicate that the apical filling materials obtained by lateral or vertical condensation leak less than those obtained by thermafil.

Analysis of Variance↗
PubMed1992

Effects of Nd:YAG laser on apical seal of teeth after apicoectomy and retrofill.

The application of Nd:YAG laser to tooth surface can change its surface permeability. The purpose of this study was to investigate the effects of Nd:YAG laser on the permeability of dentin following apicoectomy and retrofill. Sixty single-rooted teeth were randomly assigned to six groups of 10 teeth each. The six groups were arranged in three pairs, experimental and control groups. The canals of teeth in pairs 1 and 2 were cleaned, shaped, obturated, and their apical 2 mm were resected. A class I preparation was prepared and filled with amalgam in each tooth in pair 1. The apical 2 mm of each tooth in pair 3 was removed, and a class I preparation was prepared and filled with amalgam. The apical surface of resected roots in half of the samples in each pair was lased twice by using Nd:YAG laser. The duration of lasing and the number of pulses were recorded for each tooth. After application of nail polish to the unoperated surface of each tooth, the teeth were placed in 0.5% methylene blue dye for 48 h. The amount of dye penetration in sagittal sections of each tooth was measured. The amount of dye penetration was significantly lower in lased roots than in nonlased ones (p < 0.05). Based on our results, it appears that application of Nd:YAG laser reduces the permeability of resected roots.

Analysis of Variance↗
PubMed1992

Concentrations of leukotriene B4 in symptomatic and asymptomatic periapical lesions.

Twelve periapical lesions from symptomatic and asymptomatic patients (six each) were obtained and immediately frozen in liquid nitrogen. Six pulps from unerupted third molars as well as chronically inflamed gingival tissues were also obtained, frozen, and used as negative and positive controls, respectively. The concentration of leukotriene (LT) B4 was determined by reverse phase high pressure liquid chromatography. Representative samples from each group were fixed in formalin, sectioned, and stained with hematoxylin and eosin. Extremely low levels of LTB4 were detected in the uninflamed pulpal samples in comparison to those found in chronically inflamed gingival tissues and periradicular lesions. A significant statistical difference was noted between concentrations of LTB4 in periapical lesions of symptomatic patients and those found in asymptomatic patients and samples of chronically inflamed gingival tissues (p < 0.05). In addition, a positive correlation was found between the presence of symptoms, the concentration of LTB4, and presence of polymorphonuclear leukocytes in symptomatic periapical lesions. The results show presence of high concentrations of LTB4 in symptomatic human periapical lesions.

Analysis of Variance↗
PubMed1992

Anatomical relationship of the mandibular canal to its surrounding structures in mature mandibles.

A lack of agreement exists in the literature regarding the anatomical relationship of the mandibular canal to its surrounding structures such as the root apices. The purpose of this investigation was to study the spatial relationship of the mandibular canal to the posterior teeth in dried human mandibles. Twenty-two mature dried mandibles were sectioned through the root apices of the first and second premolars and molars. Second premolars and second molars had the closest distances to the canal with a mean of 4.7 mm and 3.7 mm, respectively. With a mean of 6.9 mm, the apices of the mesial roots of the first molars were farthest from the canal. The canal pathway in mature mandibles followed in S-shaped curve in 31% of the cases. In 41% of the cases it was located lingual (19%), buccal (17%), or directly inferior (5%) to the apices of the posterior teeth. In 28% of the cases the canal could not be identified clearly in the second premolar and first molar regions. In a typical S-shaped configuration the canal was located buccal to the distal root of the second molar, crossed to the lingual below the second molar mesial root, ran lingual to the first molar, and crossed back to the buccal apical to the apex of the second premolar. Based on our results it appears that the mandibular second premolar and second molar are the most likely teeth to be involved in accidental damage to the mandibular canal during root canal therapy.

Bicuspid↗
PubMed1992

Scanning electron microscopic study of the apical dentine surfaces lased with ND:YAG laser following apicectomy and retrofill.

The purpose of this investigation was to study the effects of a Nd:YAG laser on the cut surface of teeth using scanning electron microscopy (SEM). Eighteen single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. The apical 3 mm of each tooth were resected with a diamond fissure bur, and the teeth were randomly divided into two groups of nine teeth each. The resected surface of each root in one group was lased twice. The duration of lasing and the number of pulses were recorded for each tooth. The teeth were air dried, mounted on stubs, sputter-coated with gold-palladium and examined under SEM. Application of the Nd:YAG laser caused melting of apical dentine surfaces. The melted material resembled the appearance of glazed interconnected droplets. Resolidification and recrystalization of the melted areas appeared to be incomplete and discontinuous. Some areas between the glazed regions appeared similar to those of non-lased apical dentine resected root surfaces.

Apicoectomy↗
PubMed1992

Apical closure of an immature root subsequent to apical curettage.

A 7-year-old female presented with a history of trauma to the mandibular central incisor resulting in pulpal necrosis and soft tissue swelling. During apexification treatment, an ultrasonic file was separated and lodged in the periapical tissues. Surgical retrieval of the broken instrument resulted in complete curettage of the periapical tissues. Apical closure occurred following intracanal calcium hydroxide therapy. The findings suggested that hard tissue barrier formation occurred despite the absence of Hertwig's epithelial root sheath and local periapical tissues.

Calcium Hydroxide↗
PubMed1992

Managing local anesthesia problems in the endodontic patient.

Root canal therapy has a poor public image related to occasional and sometimes severe pain, and to dentists' inability to obtain profound anesthesia. Patients' apprehension, in combination with tissue inflammation, significantly lowers the pain threshold, which decreases the anesthetic's effectiveness. The best and also the first approach to achieving anesthesia is to administer a conventional block or infiltration. If profound anesthesia does not occur after this attempt, use a supplemental technique such as lingual infiltrations, PDL or intrapulpal injections. Because infiltrations are generally not effective, PDL and intrapulpal injections are preferred. The PDL is better than the intrapulpal injection because it is non-painful, safe and usually effective. The intrapulpal injection is limited and may be uncomfortable. Administer both the PDL and intrapulpal injections under back-pressure to achieve effective, but short-lived anesthesia. Special injection devices (for example, pressure syringes for the PDL) are not required for either technique. Two anesthetic types are useful. Administer 2 percent lidocaine with epinephrine for conventional and supplemental injections. For emergencies and long procedures, administer 0.5 percent bupivacaine with epinephrine to provide effective, long-lasting anesthesia and analgesia.

Anesthesia, Dental↗
PubMed1992

Esotropia following posterior superior alveolar nerve block.

Adequate use of local anesthetics is an important phase of modern dentistry. Regardless of the care used in administration of local anesthetics, unusual reactions can occur. A case is presented in which posterior superior alveolar administration of two percent Lidocaine 1/100,000 epinephrine resulted in medial rotation of the orbit (esotropia).

Abducens Nerve Injury↗
PubMed1991

The concentration of prostaglandin E2 in human periradicular lesions.

Prostaglandins (PG) have been implicated in the genesis of periapical lesions. Periapical specimens from patients with clinical signs and symptoms of chronic and acute apical periodontitis were obtained and immediately frozen in liquid nitrogen. Periradicular tissues from unerupted third molars were frozen and used as controls. The concentration of PGE2 was determined by radioimmunoassay. Low levels of PGE2 were found in the control tissues as compared with those detected in chronic and acute lesions. Significantly higher levels of PGE2 were found in acute lesions than those found in chronic lesions. The results show that acute lesions have higher concentrations of PGE2 than chronic lesions and confirm the role of prostaglandins in the pathogenesis of human periapical lesions.

Acute Disease↗
PubMed1991

Specificity of antibodies present in human periapical lesions.

Various classes of immunoglobulins have been found in human periapical lesions. The specificity of secreted antibodies against antigens egressing from the root canal system has yet to be thoroughly investigated. The purpose of this study was to test the specificity of antibodies present in human periapical lesions. Human periapical biopsies were removed and cultured as organ culture explants. Antibodies present in the lesions were extracted in the cell culture fluids. A modified enzyme-linked immunosorbent assay was used to determine the presence, type, and concentration of different classes of antibodies against a number of commonly found bacterial species present in the root canal system. The data show the presence of specific antibodies (IgG, IgM, and IgA) against all 16 microorganisms tested. Peptostreptococcus micros, Actinomyces israelii, Staphylococcus intermedius, and Fusobacterium nucleatum produced significantly high levels of IgG antibodies in these lesions.

Actinomyces↗
PubMed1991

The presence of nerve fibres in the coronal odontoblast layer of teeth at various stages of root development.

Many studies have investigated the presence of nerve fibres in the coronal odontoblast layer of mature teeth. However, little information is available on the presence of these structures in immature human teeth. The pulps of 18 human maxillary and mandibular third molars at various stages of development were collected, sectioned, and stained by the immunoperoxidase technique. The results showed the presence of numerous myelinated nerve fibres in the coronal odontoblast layer of teeth with fully formed roots. Similar observations were made in teeth with half formed roots, and in those without roots. On the basis of these results, it appears that a lack of response to vitality tests in teeth with incompletely formed roots is not wholly due to the absence of nerve fibres in the coronal odontoblast layer.

Dental Pulp↗
PubMed1991

Leukotrienes: their possible role in pulpal and periapical diseases.

Leukotrienes play an important role in inflammation and its sequelae such as pain, swelling, and bone resorption. This review covers, their history, structure, synthesis, metabolism, biological effects, inhibitors, antagonists, and their possible role in pathogenesis of pulpal and periapical disease.

Arachidonic Acid↗